The present invention relates to ternary and higher blends of fluorinated hydrocarbons and more specifically to near-azeotrope constant-boiling blends and expands upon refrigerant compositions for cooling and heating applications, as heretofore described in U.S. Pat. No. 4,810,403. Such blends are useful as refrigerants, heat transfer media, gaseous dielectrics, expansion agents, aerosol propellants and power cycle working fluids. Concern over the ozone depletion potential of certain halocarbons has resulted in a search for alternative compounds having lower ozone depletion potentials. A present day commercial binary azeotrope refrigerant widely used in supermarket refrigerators consists of 48.8 wt % chlorodifluoromethane (HCFC-22) and 51.2 wt % chloropentafluoroethane (CFC-115) and is generally referred to as Refrigerant-502. Due to the presence of chlorine in CFC-115, CClF2CF3, is expected to be subject to reduced usage because of its high ozone depletion potential. Additionally chlorine containing medium to low temperature refrigerants which may be subject to reduced usage could be replaced with all HFC containing blends described within.
In refrigeration applications, refrigerant is often lost through leaks during operation, such as through shaft seals, hose connections, solder joints, and broken lines. In addition, refrigerant may be released to the atmosphere during maintenance procedures performed on refrigeration equipment.
Most commercial refrigerants which are now used are pure fluids or azeotropes, many of these refrigerants have ozone depletion potentials when released to the atmosphere. Some nonazeotropic blends of refrigerants may also be used but they have the disadvantage of changing composition when a portion of the refrigerant charge is leaked or discharged to the atmosphere. Should these blends contain a flammable component, they could also become flammable due to the change of composition which occurs during the leakage of vapor from refrigeration equipment. Refrigeration equipment operation could also be adversely affected due to this change in composition and vapor pressure which results from fractionation.
What is needed, therefore, are substitute refrigerants which maintain important refrigerant properties of vapor pressure and nonflammability over a wide range of compositions, while also having reduced ozone depletion potential.